I'll start by quoting today's Gospel reading in the ordinary form of the Roman Rite:
As Jesus continued his journey to Jerusalem, he traveled through Samaria and Galilee. As he was entering a village, ten lepers met him.
They stood at a distance from him and raised their voices, saying, "Jesus, Master! Have pity on us!" And when he saw them, he said, "Go show yourselves to the priests." As they were going they were cleansed. And one of them, realizing he had been healed, returned, glorifying God in a loud voice; and he fell at the feet of Jesus and thanked him.
He was a Samaritan. Jesus said in reply, "Ten were cleansed, were they not? Where are the other nine? Has none but this foreigner returned to give thanks to God?" Then he said to him, "Stand up and go; your faith has saved you.
As the preacher for the papal household, Fr. Raniero Cantalamessa, says:
In the Bible, miracles are never ends in themselves; much less are they supposed to elevate the person who does them and show off his extraordinary powers, as is almost always the case with healers and wonder workers who advertise themselves. Miracles are rather an incentive for and a reward of faith. It is a sign and it must serve to draw attention to what it signifies. This is why Jesus is saddened when, after having multiplied the loaves of bread, he sees that they did not understand what this was a sign of (cf. Mark 6:51).
In this case, the mass miracle of healing the lepers is clearly a sign of our salvation. In the scheme of divine revelation, the sign is efficacious as such precisely because it occurred as related. But what it signifies is itself the chief miracle. Through and in virtue of the Mystical Body of Christ, the Church, "salvation"—i.e., the healing of our souls that occurs when they are elevated into partakers of the divine nature"—is offered to us collectively as members thereof. Our choice whether or not to accept the gift of the faith that saves is of course individual; but it is only made possible for us, and only has efficacy for us, in and through the Mystical Body of which we become part by baptism. Yet most of us, most of the time, don't care about that as we ought. Often we are hardly aware of it. The ingratitude of the nine lepers is a sign of our own indifference and ingratitude. Those of us Christians who are not, already, saints are "the other nine."
I recognize myself among them. For me, gratitude to God is a real challenge. I don't much care for my life as it is. Indeed, it is an ongoing struggle for me to extirpate the wish that my gifts and my very self were radically different from what they are. So instead of thanking Jesus for his inestimable gift of salvation and leaving myself at his loving disposal, I often go off wondering how long before I'm let out on parole. I'd much prefer to be part of his company, part of the Twelve. It would seem so much more meaningful, so much more exciting. I'd rather not be told "Stand up and go; your faith has saved you." I want to stay, but I can't; consequently, I'm ungrateful. And my ingratitude destroys the intimacy I need and seek. Having been given the miracle I need, I become part of the other nine simply so as not to be told what I don't want to hear—even though I've already been told all I need to hear, which I didn't deserve to begin with.
The only solution is the spirit of self-offering exemplified, and made possible, by Jesus on the Cross. Amid all our own problems, which are intertwined with those of the Church, let us remember to be grateful for whatever in our lives is not, itself, sin. It all comes from God and is part of the miracle of healing that is our salvation. Let us offer it all to the cosmic Christ to do with as he wills.